This invention relates to an improved process of treating fabrics constructed of synthetic thermoplastic fibers to impart flame resistance and is specific to the use of cyclic phosphonate esters having flame retardant properties. Also described are procedures in which flame resistance is imparted to the fabric and the fabric is heatset, dyed or both heatset and dyed in the same procedure. These esters serve to swell the thermoplastic fiber and allow introduction of a dyestuff into the fiber.
For certain applications and end uses, many fabrics and composites must meet specific flammability standards. To meet these standards, it is sometimes necessary to apply flame retardant chemicals. Cyclic phosphonate esters are a known class of flame retardants used for treating textiles and plastics. The supplier recommends diluting these flame retardant materials with up to about 90% of water and applying the resulting solution by padding in a pad bath followed by drying then heating in an oven at temperatures up to 420.degree. F.
This invention uses flame retardants that withstand elevated temperatures and are liquids at elevated temperatures. The flame retardant is used in "neat", undiluted or substantially undiluted form. When dyeing is also desired, a suitable dye is dissolved in the flame retardant to simultaneously dye and flame retardant treat the synthetic thermoplastic fibers.
The elevated temperatures used in the flame retarding process are also effective temperatures to heatset the fabric. This is easily accomplished when the fabric is kept under the appropriate tension as the fabric is exposed to the operational temperatures used to impart flame resistance to the fabric. In another embodiment, this invention simultaneously flame retardant treats and dyes thermoplastic fibers in a dyebath containing only the flame retardant and a dissolved disperse and/or anionic dye. Brief immersion of the fabric to be dyed into a heated bath causes the cyclic ester flame retardant and the dye to diffuse into the thermoplastic fibers. Time and temperature requirements are easily determined by a short series of examples. With proper tension controls, the fibers in fabric form can be dyed flame retardant treated and heatset in the same operation. Excess liquid on the fabric surface is conveniently removed by vacuum or other means and returned to the bath. Remaining liquid on the fabric is removed by scouring; the scoured fabric can be dried, for example in a tenter oven where tension is easily controlled.
In addition to the dyestuff(s), the treatment bath or liquid may also include other finishing chemicals and processing adjuvants amenable to application by such a process, including UV stabilizers, antistats, soil release agents, and the like.
It is therefore an object of this invention to both dye and flame retardant treat synthetic thermoplastic fibers, excluding the simultaneously flame retardant treating and dyeing of polyaramid fibers which is the subject of copending application Ser. No. 871,389, now U.S. Pat. No. 4,752,300, identified above, in a single step and to provide a dyed product that has flame resistant qualities. Candidate thermoplastic fibers include nylon, high-tenacity nylon, polyester, acetates and acrylic fibers.
It is also an object of this invention to simultaneously flame retardant treat and heatset fabrics made of synthetic thermoplastic fibers.
Another object of this invention is to simultaneously flame retardant treat and dye fabrics made of synethetic thermoplastic fibers.
Another object of this invention is to simultaneously flame retardant treat, dye and heatset fabrics made of synthetic thermoplastic fibers.
These and other attributes of the invention are realized from the detailed disclosure that follows.